[chronojump] Fixed a crash on dispose cairobars encoder when drawingarea has not been shown yet

[Xavier de Blas <xaviblas src gnome org>]

commit 3777021302ac8640816e9ac6e3e3e50fd461d457
Author: Xavier de Blas <xaviblas gmail com>
Date:   Tue Apr 5 12:58:39 2022 +0200

    Fixed a crash on dispose cairobars encoder when drawingarea has not been shown yet

 src/gui/cairo/generic.cs | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
---
diff --git a/src/gui/cairo/generic.cs b/src/gui/cairo/generic.cs
index b83b185b8..1dc06db0d 100644
--- a/src/gui/cairo/generic.cs
+++ b/src/gui/cairo/generic.cs
@@ -58,7 +58,7 @@ public abstract class CairoGeneric
           */
        protected void endGraphDisposing(Cairo.Context g, ImageSurface surface, Gdk.Window window)
        {
-               if(surface != null)
+               if(surface != null && window != null)
                {
                        using (Context gArea = Gdk.CairoHelper.Create (window))
                        {